This invention relates generally to mattress foundation structures and more particularly to a box spring assembly of a type which utilizes non-coil springs. Box spring assemblies of this general type have been known since 1964, the first such spring assembly being disclosed in U.S. Pat. No. 3,286,281. Subsequently issued patents disclosing the same general type of box spring assembly are: U.S. Pat. Nos. 3,487,480; 3,506,987; 3,574,240; 3,574,241; 3,665,529; 3,680,157; 3,755,833; 3,824,639; 3,852,838; 4,060,862; 4,120,058; 4,131,961; 4,195,376; 4,218,790; 4,238,861; 4,251,892; and 4,253,208. Box spring assemblies of the general type shown in the above list of patents, all of which are assigned to the assignee of this application, are advantageous with respect to the conventional box spring assemblies using coil springs because they provide a desired stiffer foundation for the mattress and contain a reduced amount of wire. These box spring assemblies are also advantageous from the standpoints of prolonged service life, ease of assembly, and cost of manufacture.
Additional box spring assemblies of this general type are shown in U.S. Pat. Nos. 3,546,723; 3,596,299; 3,722,013; 3,825,960; 3,833,948; 3,835,485; 3,869,740; 3,990,121; and 4,000,531.
The present invention provides a box spring assembly which utilizes a wire deck or grid and a supporting spring that is different from the formed wire springs utilized in the patented box spring assemblies discussed above. The spring in the present box spring assembly is improved from the standpoint of providing desired qualities of firmness, internal strength, and edge support to the wire deck in addition to being readily connectible to the deck by conventional wrap-around clips. The improved box spring assembly of this invention also includes improved corner springs for supporting the corners of the deck on the frame and improved cross rails which support the springs on the frame.